Ice hockey's Bracknell Bees and Thames Valley Tigers basketball club are both seeking new owners following chairman John Nike's decision to pull out.
Bracknell Bees are now facing an uncertain future
Nike, whose cash helped Bees win this season's British National League and Winter Cup, has withdrawn his support to focus on other business interests.
Nike's ownership of both franchises will officially end on 6 May.
Martin Weddell, Bees chief executive, said: "John has supported these sports for years. It wasn't an easy decision."
Weddell also blamed "escalating costs and the pressures of the Inland Revenue which continues to pressurise John Nike for his support in the past" for the move.
The news is another blow for ice hockey's British National League (BNL) following Edinburgh Capitals' annoucement that they are to join Newcastle Vipers in defecting to the rival Elite League.
The futures of the four remaining BNL clubs - Dundee Stars, Fife Flyers, Guildford Flames and Hull Stingrays - are now also in doubt.
Unlike Capitals and Vipers, they are not expected to join the Elite League.
That leaves signing up to the English Premier League, or setting up a new league, as their only options.